The present invention relates to threaded fasteners and more particular to a threaded fastener having a braking action to eliminate strip-out during application of the fastener. In addition, the present invention relates to a threaded fastener having a locking action to eliminate loosening of the fastener, after it is set in place.
In the field of threaded fasteners, and in particular, threaded fasteners to be employed with sheet materials, there is a need for a fastener which exhibits the ability to prevent strip-out of the fastened material under high torque application of the fastener. Generally, the use of power screw drivers for assembly of sheet metal structures has given rise to the need for a fastener which may be driven with a high torque setting on the driver, but which will have a braking action of a magnitude sufficient to counteract the driver torque and stop the rotation of the fastener in the workpiece prior to strip out of the threads within the workpiece.
Co-existent with this requirement, there is often the need to provide a threaded fastener which has the ability to be engaged in the workpiece or workpieces, and locked in place without the requirement for additional lock washers, either permanently attached to the fastener, or as a secondary fastening element.
Various fastener structures have been disclosed having features intended to solve the above problems typical of which are disclosed in U.S. Pat. Nos. 3,605,845 issued Sept. 20, 1971 to G. H. Junker, 3,389,734 issued June 25, 1968 to C. E. Gutshall and 4,310,272 issued Jan. 12, 1982 to Rich, et al. Many of such prior art devices have proved useful in achieving the desired results, and have been successful in the marketplace.
However, the present invention has as an object to provide an improved fastener of the type disclosed above, which is simple and less costly to manufacture than prior art fasteners which are intended to achieve a high torque braking action or the locking feature, required for a particular application.
The invention has as a further object to provide a method of manufacturing a fastener exhibiting the quality of preventing strip out, or a locking action, which method is simple and less costly than those of the prior art.
A further object of the invention is to provide a die set for manufacturing a fastener of the type set forth above which is effective to produce the above-described fastener in a single heading operation.